<?php

$nome_img_topo = $row->field_field_imagem_topo[0]['rendered']['#item']['filename'];
$url_img_topo = '/sites/default/files/'.$nome_img_topo;

?>

<div id="imagem_slide" style="background-image: url('<?php print $url_img_topo;?>');">
    <?php print $field->original_value;?>
</div>